Advancing Subseasonal PredIctions at Reduced computational Effort

Introduction

The new frontier for weather prediction is the so-called subseasonal time scale of two weeks to two months ahead. To take preventive measures at an early stage, reliable forecasts on this time scale are becoming increasingly important for multiple socio-economic sectors.

Subseasonal Predictability

Subseasonal predictability can be gained from recurring patterns in the Earth system. ASPIRE will focus on one of these, namely modes of tropical convective variability. Long-standing systematic errors due to the parametrization of processes in numerical weather prediction models prevent the predictability of these modes from being exploited.

Computational Challenges

Simply running models at a resolution high enough to resolve tropical convection is not feasible due to high computational costs. Taking advantage of three recent developments, ASPIRE will explore new ways to better exploit the intrinsic predictability of tropical convective modes without exhausting the currently available computing resources.

Unique Approach

The uniqueness of ASPIRE is its cross-disciplinary approach that builds on my experience in atmospheric dynamics and predictability, numerical modeling, and machine learning (ML).

1. Identifying Forecast Errors: ASPIRE will identify the source regions and pathways of tropical forecast errors that prevent the intrinsic predictability from being exploited using a new set of subseasonal ensemble hindcasts.
2. Quantifying Added Value: ASPIRE will quantify for the first time the added value of locally confined kilometer-scale resolution in the source regions identified before, and generate probabilistic predictions from deterministic forecasts through ML-based post-processing.
3. Developing ML Approaches: To enable simulations at kilometer-scale resolution in operations, ASPIRE will develop ML approaches that emulate the integrated effect of the resolved convection in the tropics at substantially reduced costs.

Expected Outcomes

If successful, this approach would be a breakthrough towards improved operational weather forecasts at substantially lower computational costs, for a global socio-economic benefit.